Radial-piston pump with improved cooling and lubrication



- 19. 1969 L..:BUD"ECV2KER 3,4615809 RADIAL-PISTON PUMP WITH IMPROVED COOLING AND LUBRICATION Filed March 13, 1968 2 Sheets-Shet 1 m //4 v I,

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INVENTOR VOW/6 BUDECKEE B? W g 106 Aug. 19, 1969 L. BUDECKER 3 6 RADIAL-PISTON PUMP WITH IMPROVED COOLING AND LUBRICATION Filed March 13, 1968 '2 Sheets-Sheet 2 INVENTOR Al/flW/G BUDEC/KEB QIwIQETRw ATTORNEY I "United States Patent 3,461,809 RADIAL-PISTON PUMP WITH IMPROVED COOLING AND. LUBRICATION. Ludwig Budecker, Frankfurt amMain, Germany, asslgnor to Alfred Teves, G.m.b.H., Frankfurt am Main, Germany, a corporation of Germany Filed Mar. 13, 1968, Ser. No. 712,817 Claims priority, application Germany, June 22, 1967,

Int. (:1. F04b1/04, 39/02 U.S. Cl. 103-174 7 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a radial-piston pump supplying hydraulic pressure by means of an eccentric shaft which-rotates in a cylinder housing in which the pumping pistons are radially disposed.

Hydraulic pumps of this type, preferably employed when high pressures are involved, demand very fine machining of the component parts, extremely close tolerances and the maintenance of constant lubrication between the moving parts. The latter task in particular requires continuous removal of the heat associated with high pressures and the correlated friction between moving parts. Furthermore, the efficiency of other pump com ponents is liable to be aflected by a thermal distortion of the lubricating means or by their decomposition into substances which are ineffectual as lubricants or incompatible with the metallic and non-metallic parts with which they are in contact.

It is therefore the primary object of this invention to supply the working elements of a radial piston pump with the moderate environmental temperatures necessary to maintain the effective lubrication of the moving parts.

These objects and others which will become apparent hereinafter are attained, in accordance with the present invention, by routing the working hydraulic fluid on its Way from the fluid reservoir to the piston cylinder intake chamber so as to flow past heat-sensitive surfaces and to carry away the undesirable heat. Specific-ally, the circuitous flow pattern leads fresh cool hydraulic fluid in and out of the rotor shaft which carries the slidable sleeve designed to displace the piston and past and through the jacket or sleeve surrounding the eccentric.

According to a more specific feature of this invention, the eccentric shaft is rotatably received in a blind bore of the pump or cylinder housing which communicates, at its closed end, with the intake port of the pump and delivers hydraulic fluid to an annular suction chamber within the housing communicating with the pumping cylinders. At least part of the fluid delivered from the intake portion to the suction chamber is passed through an axial bore formed in the eccentric shaft at its end proximal to the closed end of the axial bore of the housing. Spaced from this end of the shaft, there is provided and eccentric portion around which a bearing sleeve or jacket is disposed with peripheral clearance, the axial bore of the shaft opening within the sleeve via one or more radial ports formed in the eccentric portion of the shaft. The sleeve is, according to another feature of this in- 3,461,809 Patented Aug. 19, 1969 "ice vention, formed with openings communicating between its interior (with which the radial ports communicate) and the annular space in the axial bore of the housing surrounding the sleeve and into which the pistons project tocontact the sleeve. This annular space is, in turn, connected with the suction chamber of the housing by one or more channels.

Still another feature of this invention provides, between the suction pump and the annular space surrounding the sleeve or in the sleeve itself, one or more constrictions adapted to apply a pressure drop between the suction chamber and the fluid passage through the sleeve and axial bore of the shaft to ensure fluid flow through this passage for-lubrication of the co-operating surfaces of the eccentric portion and the sleeve as well as the cooperating portions of the sleeve and the pistons. The system may be embodied in various ways, namely, by providing the intake portion or side of the pump in fluid communication with the closed end of the axial bore so that the lubricant and cooling fluid also passes axially through the bore from the closed end into the suction compartment. In an alternative construction, the annular space surrounding the ring or sleeve may communicate with the suction chamber via the axial bore at the closed end of the latter while the intake port or side of the pump communicates with the space surrounding the ring. In this construction, the coolant and lubricant flows initially through and around the bearing ring or sleeve, thence through the radial bores or bore of the eccentric portion of the shaft and the axial bore of the latter into the suction compartment.

The system may be provided with a throttle or constriction between the intake side or port and the suction component so that a path of lower pressure loss is provided along the passageway around the bearing ring or sleeve and through the shaft, then is formed between the intake port and the suction compartment; alternatively, a throttle or constriction may be formed in the channel communicating between the space surrounding the bearing ring or sleeve while the suction compartment is connected with the intake port via another channel to partition fluid flow between the lubricating and cooling passageway and direct flow to the suction compartment.

The system described generally above has the advantage that at least part of the hydraulic fluid displaced by the pump traverses the eccentric shaft and the bearing surfaces of the sleeve therearound before passage into the suction compartment and thus provides a constant stream of cool fresh lubricant and coolant.

The above and other objects, features and advantages of this invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view, in part, showing another embodiment of my invention;

FIG. 1A is an end view, with the cover plate removed, of the embodiment of FIG. 1; and

FIG. 2 is an axial cross-sectional View, in part, of another embodiment.

Cooling accompanied by high pumping efiiciency is provided, according to the embodiment of FIGS. 1 and 1A through constrictions interposed in the fluid flow which are designed to create a pressure difference.

In FIGS. 1 and 1A, there is shown a radial-piston pump whose housing 101 has a cylinder block 101b and a pair of cover plates 101a and 101s bolted to the cylinder block and defining the fluid conduits as will be apparent hereinafter. A fluid-intake port 114 is provided in the cylinder block 101b and communicates with a radially extending chamber 115 defined in the axial bore 128 of the cylinder housing 101b between the front face 111 of the shaft 102 and the cover 1010, this compartment lying in a plane perpendicular to the axis of rotation of the shaft 102. As shown by the broken-line arrows, the second conduit connecting the port 114 with the annular suction chamber 121 is completed by an axially extending channel 115' surrounding a boss 10112 at the end of the shaft and a further annular chamber 115" defined between the cover 1010 and the cylinder body 101b. The first conduit is here constituted by the axial bore 110 in the shaft 102 and a plurality of axially spaced radial orifices 113, 113a opening into the annular clearance 122 within the bearing sleeve 103. The latter is formed with notches 124 along its opposite annular ends and with radial apertures 124', all equispaced about the bearing sleeve, to connect the annular clearance 122 with the annular space 125 surrounding the sleeve. A passage 126 connects the space 125 with the suction chamber 121 via an annular chamber 126' which also serves to collect leakage fluid behind the bearing seal 127. The pistons 104 are here applied by fluid pressure against the bearing sleeve 103 and are axially shiftable in the cylinder 119. A plate-type check valve 120 is employed and the plugs 120 close the heads of the cylinders 119. Bores 107 collect the fluid under pressure from cylinders 119 and deliver this fluid to the high-pressure discharge port 103 via an annular discharge chamber 107. According to the present invention, the clearance 122 may constitute a constriction forcing the fluid flow from the intake port 114 to the suction chamber 121 to be split between the first conduit 114, 115, 110, 113, 122, 124, 124, 125, 126, 126 and the second conduit 114-, 115, 115', 115", 121, thereby providing high pumping efficiency and appropriate lubrication and cooling. The constriction can additionally or alternatively be formed by apertures 124 and 124'.

In FIG. 2, the cylinder body 201.) is flanked by a pair of cover plates 201a and 201a but has an intake port 214 connected by a passage 214a directly to the annular space 225 surrounding the bearing sleeve 203. The bearing sleeve 203 surrounds the eccentric portion 215 of the shaft 202 and is provided with apertures 224 and 224' as previously described. The sleeve 203 is mounted upon the eccentric portion 215 with an annular clearance 222 from which the cooling and lubricating fluid is delivered to the axial bore 210 of the shaft by radial orifices 213 and 213a. The sleeve 203 also displaces the pistons 204 in the bores 219 while the suction chamber is formed at 221 and each piston co-operates with the check valve 220, a channel 207 and a chamber 207 for the high-pressure fluid as previously described. The constriction is here provided at 226 in a passage 226 conmeeting space 225 with the annular chamber 226' and the suction chamber 221. The constriction or throttle 226" thus creates a split flow between the first conduit 214, 214a, 225, 224, 224', 213, 213a, 210, 215, 215', 221 and a second conduit 214, 214a, 225, 226, 226", 226', 221. Again lubrication and high pumping efficiency are obtained. Chambers 126' and 226 also connect a leakage path around the shafts 102, 202 just behind the bearing seals 127, 227 with the suction chamber, the leakage path extending from the spaces 125, 225.

The pistons 104 and 204, which are shown in their most outwardly extreme positions, represent a plurality of similar pistons disposed along common radial planes P and P of the pumps and angularly equispaced about the axis A and A thereof. The pistons may be springbiased against the bearing sleeve 103, 203 as, for example, described in the commonly assigned concurrently filed copending application Ser. No. 712,461 and bearing the same title as the present application. Here, however, the fluid pressure applied to the pistons 104i and 204 at the surfaces 104a and 204a retain the pistons against the bearing sleeves.

Pumping action is effected by rotation of the eccentric shafts 102, 202 about their respective axes A and A to radially shift the pistons in the direction of arrows and 205 respectively. As the pistons 104, 204 shift radially inwardly from their positions shown in the drawing, the leading edges 104' and 204 recede behind the edge 119' or 219' of the respective cylinder at the point at which it communicates with the corresponding suction chamber 121, 221 to admit fluid from the suction chamber into the cylinder 11? 219 ahead of the piston. Continued rotation of the shaft 102, 202 drives the pistons 104, 204- radially outwardly so that the edges 104, 204, become flush with the edges 119, 219, and block backflow of fluid from the cylinders 119, 219 to the suction chambers 121, 221. Still further displacement of the shafts 102, 202 drives the pistons 104, 204 radially to force the fluid ahead of these pistons past the respective check valves 120, 220 and thence into the passages 107, 207' leading to the pressure chamber 107, 207. From the latter, the fluid is supplied to the load via the discharge ports 108, 208 in the usual manner.

The invention described and illustrated is believed to admit of many modifications within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the appended claims.

What is claimed is: 1

1. A radial-piston pump having a housing formed with an axially extending housing bore; an eccentric shaft rotatably received in said housing bore and provided with an eccentric portion therealong; at least one cylinder formed in said housing and slidably receiving a piston driven by said shaft; a suction chamber and a fluid-discharge chamber formed in said housing and communicating with said cylinder for displacement of fluid from said suction chamber to said discharge chamber upon rotation of said shaft and reciprocation of said piston; a fluidintake port formed in said housing and communicating with said suction chamber, a sleeve surrounding said eccentric portion of said shaft and acting upon said piston for displacing same upon rotation of said shaft; means forming at least one passageway having at least a portion extending through said shaft and communicating with one of said chambers while opening within said sleeve and between said sleeve and said eccentric portion for cooling the pump and lubricating said sleeve, said passageway connecting said fluid-intake port with said suction chamber, said shaft having an extremity terminating in said housing and defining part of said passageway, said portion of said passageway being formed as an axial bore in said shaft and opening at said extremity thereof, said eccentric portion in said shaft being formed with at least one radial orifice communicating with the axial bore of said shaft and opening within said sleeve, said sleeve defining an annular inner clearance with said eccentric portion of said shaft and an annular outer space with a wall of said housing both surrounding said sleeve, said orifice opening into said clearance, said sleeve being formed with at least one channel connecting said clearance with said space, said channel, said radial orifice, said axial bore in said shaft and said part of said passageway constituting a first fluid conduit connecting said intake port with said suction chamber, said housing being provided with a second fluid conduit connecting said intake port with said suction chamber; and at least one constriction formed along one of said conduits for inducing a pressure drop between said space and said suction chamber to branch fluid flow from said intake port to said suction chamber at least partly through said first conduit.

2. The improvement defined in claim 1 wherein said channel is one of a plurality of radial perforations formed in said sleeve.

3. The improvement defined in claim 1 wherein said channel is one of a multiplicity of notches formed in the opposite axial ends of said sleece.

4. The improvement defined in claim 1 wherein said clearance constitutes said constriction.

5. The improvement defined in claim 1 wherein said second conduit includes a passage formed in said housing and connecting said space with said suction chamber, said constriction being constituted as a throttle orifice provided along said passage.

'6. The improvement defined in claim 1 wherein said piston and said cylinder lie in a radial plane of said housing, said orifice lying substantially in said plane and said axial bore of said shaft extending through the latter substantially to said radial plane.

7. The improvement defined in claim 1, further comprising bearing means in said housing remote from said extremity and means forming a leakage path along said shaft to the region of said bearing means and thence from said bearing means to said suction chamber.

6 References Cited UNITED STATES PATENTS 2,394,285 2/1946 Bevins 103174 2,612,837 10/195'2 Midgette 103--174 5 2,693,150 11/1954 Pickard et al. 103-174 2,801,596 8/1957 Sewell 103174 2,818,816 1/1958 Christenson l03174 2,836,120 5/1958 Nauar-ro 103174 2,851,952 9/1958 Lane 103-174 3,125,034 3/1964 Lucien et a1. 103174 FOREIGN PATENTS 902,097 8/ 1945 France.

15 HENRY F. RADUAZO, Primary Examiner US. Cl. X.R. 230-206 

